Sustainable solutions for reducing plastic pollution must not only be good for the environment, but also competitive with plastics in terms of both cost and performance. The present invention involves vacuum forming molded fiber containers, and trimming and otherwise removing excess fiber material during the drying stage of manufacture.
Molded paper pulp (molded fiber) can be produced from old newsprint, corrugated boxes and other plant fibers. Today, molded pulp packaging is widely used for electronics, household goods, automotive parts and medical products, and as an edge/corner protector or pallet tray for shipping electronic and other fragile components. Molds are made by machining a metal tool in the shape of a mirror image of the finished package. Holes are drilled through the tool and then a screen is attached to its surface. The vacuum is drawn through the holes while the screen prevents the pulp from clogging the holes.
The two most common types of molded pulp are classified as Type 1 and Type 2. Type 1 is commonly used for support packaging applications with 3/16 inch (4.7 mm) to ½ inch (12.7 mm) walls. Type 1 molded pulp manufacturing, also known as “dry” manufacturing, uses a fiber slurry made from ground newsprint, kraft paper or other fibers dissolved in water. A mold mounted on a platen is dipped or submerged in the slurry and a vacuum is applied to the generally convex backside. The vacuum pulls the slurry onto the mold to form the shape of the package. While still under the vacuum, the mold is removed from the slurry tank, allowing the water to drain from the pulp. Air is then blown through the tool to eject the molded fiber piece. The part is typically deposited on a conveyor that moves through a drying oven.
Type 2 molded pulp manufacturing, also known as “wet” manufacturing, is typically used for packaging electronic equipment, cellular phones and household items with containers that have 0.02 inch (0.5 mm) to 0.06 inch (1.5 mm) walls. Type 2 molded pulp uses the same material and follows the same basic process as Type 1 manufacturing up the point where the vacuum pulls the slurry onto the mold. After this step, a transfer mold mates with the fiber package on the side opposite of the original mold, moves the formed “wet part” to a hot press, and compresses and dries the fiber material to increase density and provide a smooth external surface finish. See, for example, http://www.stratasys.com/solutions/additive-manufacturing/tooling/molded-fiber; http://www.keiding.com/molded-fiber/manufacturing-process/; Grenidea Technologies PTE Ltd. European Patent Publication Number EP 1492926 B1 published Apr. 11, 2007 and entitled “Improved Molded Fiber Manufacturing”; and http://afpackaging.com/thermoformed-fiber-molded-pulp/. The entire contents of all of the foregoing are hereby incorporated by this reference.
Presently know techniques for vacuum forming fiber-based, molded pulp packaging products (e.g., food containers) do not contemplate in-line die cutting of the container.
Methods and apparatus are thus needed which overcome the limitations of the prior art.
Various features and characteristics will also become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background section.